Is it possible to scale and rotate the 'image for clone tool'?
The answer is "no", you cannot rotate the clone source in the Image Editor. But an alternate is available that DOES allow you to rotate and scale your image source, and that is by loading the clone source instead as a Brush Texture in the properties panel while using the TexDraw brush (default texture paint).

The Texture then needs to be set to 'Stencil' in the tool bar Texture panel. Zoom out, and then move the stencil with RMB, scale it with Shift-RMB, and with Ctrl-RMB you can rotate it. The same thing can be done with the Texture Mask set to Stencil, but use Alt-RMB to move, Alt-Shift-RMB to scale and Alt-Ctrl-RMB to rotate.

This same set up works in the 3d view for painting directly on your 3d textured object. Have some fun!

edit: Also you can use the Stencil Widget by Kgeogeo that allows to use a lot of controls on the stencil texture/texture mask